Japanese Patent Application (OPI) No. 165054/84 describes heat developable light-sensitive materials comprising a combination of a dye developer, i.e., a compound having both a developer for a sliver halide and a dye in one molecule, with a silver halide. (The term "OPI" as used herein means an "unexamined published application".) When the heat developable light-sensitive material is heated in the presence of a base and/or a base precursor after or simultaneously with imagewise exposure, the dye developer is oxidized and immobilized in an area where the development has taken place, whereby an imagewise distribution of a mobile non-oxidation type dye developer is formed in negative relation to the silver image. If this mobile non-oxidation type dye developer is transferred to a dye-fixing material, a dye image is formed in positive relation to the original.
However, since the dye developer as used in the heat developable light-sensitive material easily diffuses under an alkaline condition, it moves to other layers at a stage which is too soon before it has been immobilized upon the reaction with the exposed silver halide, whereby the density of a light part which should have essentially become white becomes high, resulting in worsening not only the image identification but also the color separation.